package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
//        缓存穿透
//        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL, TimeUnit.MINUTES);

            //互斥锁解决缓存击穿
//        Shop shop = queryWithMutex(id);
        //逻辑过期解决缓存击穿
        //todo 记着把时间改回来
        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY,id,Shop.class,this::getById,20L, TimeUnit.SECONDS);
        if(shop == null)
            return Result.fail("店铺不存在");
        return Result.ok(shop);
    }
    //缓存穿透
    public Shop queryWithPassThrough(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isNotBlank(shopJson))
        {
            //3.存在，则返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        if(shopJson != null)
        {
            return null;
        }
        //4.不存在，则查询数据库
        Shop byId = getById(id);
        //5.数据库不存在，返回错误
        if(byId == null) {
            stringRedisTemplate.opsForValue().set(key, "",CACHE_NULL_TTL ,TimeUnit.MINUTES);
            return null;
        }
        //6.存在,则写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(byId),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //返回
        return byId;
    }




    //互斥锁解决缓存击穿
    public Shop queryWithMutex(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isNotBlank(shopJson))
        {
            //3.存在，则返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        if(shopJson != null)
        {
            return null;
        }
        //4.实现缓存重建
        //4.1 获取互斥锁
        String lock = LOCK_SHOP_KEY + id;
        Shop byId=null;
       try {
           boolean isLock = tryLock(lock);

           //4.2 判断是否获取成功
           //4.3 失败 获取锁失败，则休眠并重新尝试获取锁
           if (!isLock) {
               Thread.sleep(50);
              return queryWithMutex(id);
           }

           //4.4 成功，返回
           byId = getById(id);
           //测试
           Thread.sleep(200);
           //5.数据库不存在，返回错误
           if (byId == null) {
               stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
               return null;
           }
           //6.存在,则写入redis
           stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(byId), CACHE_SHOP_TTL, TimeUnit.MINUTES);
       }catch (InterruptedException e)
           {
               throw new RuntimeException(e);
           }
       finally {
           //4.6 释放锁
           unLock(lock);
       }
        return byId;
    }

private  static  final ExecutorService CATCH_REBUDID_EXECUTOR = Executors.newFixedThreadPool(10);
    public Shop queryWithLogicalExpire(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isBlank(shopJson))
        {

            return null;
        }
        //4.命中，需要先把json反序列化为对象
        RedisData rd = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject) rd.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        //5.判断是否过期
        if(rd.getExpireTime().isAfter(LocalDateTime.now()))
        {
            //5.2 未过期，直接返回
            return shop;
        }

        //6.缓存重建
        //6.1 获取互斥锁
        String lock = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lock);
        //6.2 判断是否获取成功
        if(isLock)
        {
            //6.2.1 成功，开启独立线程，实现缓存重建
            CATCH_REBUDID_EXECUTOR.submit(()->{
                try {
                    this.saveShop2Redis(id, 20L);
                }catch (Exception e)
                {
                    throw new RuntimeException(e);
                }
               finally {
                    unLock(lock);
                }

            });
        }

        //6.3 失败，返回错误
        //6.4 成功，返回数据
        //7.返回
        return shop;
    }

    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }




    public  boolean tryLock(String key)
    {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    public void unLock(String key)
    {
        stringRedisTemplate.delete(key);
    }

    @Transactional
    @Override
    public Result updateImpl(Shop shop) {
        Long id = shop.getId();
        if(id == null)
            return Result.fail("店铺id不能为空");
        updateById(shop);

        //删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }
}
